Two filament lamp with selector or switch



y 1966 J. K. WEBB, JR 3,260,888

TWO FILAMENT LAMP WITH SELECTOR OR SWITCH Filed Nov. 19, 1962 INVENTOR.

JOHN K. WEBBu/R.

BY WW 7 W United States Patent r 3,260,888 TWO FILAMENT LAMP WITH SELECTOR OR SWITCH John K. Webb, Jr., 4156 Aldebaran Way, Mobile, Ala. Filed Nov. 19, 1962, Ser. No. 238,807 1 Claim. (Cl. 315-68) This invention relates to incandescent filament lamps that are more commonly known as light bulbs.

Conventional light bulbs have only one filament and, thus, it is well known that when the filament burns out, the lamp is inoperative. Although the filament is materially only a small part in the lamp, it is the principal reason for the lamp becoming inoperative. Usually, a filament is designed to last approximately 1,000 hours, and when it fails, it, of course, cannot be replaced without replacing the whole bulb.

It is, therefore, a principal object of the present invention to provide a light bulb .of the incandescent type which has an extended period of usefulness, substantially equal to twice that of previous bulbs.

A further object is to provide such a light bulb that can readily be manufactured in such places engaged in lamp manufacturing with a minimum change in production means.

A further object is to provide an incandescent light bulb suitable for use in the home, office and other places, and which light bulb has means that can be easily and conveniently manipulated, as for example, by the housewife, to extend the life of the light bulb.

A further object is to provide a double-life light bulb that is suitable for uses such as for stop lights, caution lights and the like, where for safety reasons it is desirable to have a light bulb in which means is available for extending the life of the light bulb in case it burns out and another bulb is not immediately available.

A further object is to provide a double-life light bulb in which the extended use thereof results in considerable savings in time, money and material.

A further object is to provide a light bulb having two filaments and a current-directing plug for directing electrical current through one of the two filaments.

A further object is generally to improve the design and construction of light bulbs.

The means by which the foregoing and other objects of the present invention are accomplished and the manner of their accomplishment will be readily understood from the following specification upon reference to the accompanying drawings, in which:

FIG. 1 is a longitudinal sectional view of the light bulb of the present invention.

FIG. 2 is an enlarged exploded view of the base parts of the light bulb.

FIG. 3 is an exploded view of the current-directing plug.

Referring now to the drawings in which the various parts are indicated by numerals, light bulb 11 of the present invention is constructed, in general, in the usual mannet of an incandescent light bulb and, thus, comprises a base 13, a mount 15, and an airtight glass envelope or shell 17. Mount 15, in elfect, is an inwardly protruding portion of shell 17 and includes a tubular stem 19, an integrally formed cylindrical arbor 21 reduced from tubular stem 19 as at step portion 23, and a terminal portion 25.

Incandescent elements of the present invention include a first filament 27 and a second filament 29 which are supported and connected respectively by first, second and third lead-in wires 31, 33 and 35. The lead-in wires serve as electrical conductors and are connected to the filaments 27, 29 as follows: First lead-in wire 31 is connected to first filament 27 adjacent one end of the first 3,268,888 Patented July 12, 196 6 filament as at point 37, and second lead-in wire 33 is connected to second filament 29 adjacent one end of the second filament as at point 39. Third lead-in wire 35 is connected to filaments 27, 29 adjacent the opposite ends of the filaments from points 37, 39 as at points 41, 43, respectively. The filaments are additionally supported as by small support wires. 45 embeddedly set in terminal portion 25 of mount 15, as is the conventional practice. Although the filaments 27, 29 are herein referred to and described as two filaments, it will be understood that in actual practice the same result can be obtained by using one length of filament between lead-in wires 31, 33 and connecting lead-in wire 35 to the midpoint of the one filament to divide the filament into two halves, namely, first filament 27 and second filament 29. Thus, when the terms first filament 27 and second filament 29 are used, they denote the respective filaments or portions thereof respectively between lead-in wires 31 and 35, and between lead-in wires 33 and 35, whether they be two separate filaments or one filament effectively divided into two filaments.

Referring now to the lower part of the light bulb 11, as shown in the figures, the collar 53 of base 13 is similar in appearance and function to the collars used in conventional light bulbs, and comprises essentially a hollow cylindrical metal structure having an inner surface 55, an outer surface 57 and, additionally, is formed to provide external threads 59. The upper end of collar 53 terminates in a flared portion 61, and the opposing lower end portion extends inwardly and terminates in a circular aperture 63.

An insulator 65 is provided, preferably formed of glass material and in such a manner as to be integral with collar 53. As best shown in FIG. 1, insulator 65 conforms with the inner surface 55 and aperture 63 and is fixedly secured thereto. Insulator 65 includes a conical surface 67, which intersects a lower surface 69, and an upper surface 71 oppositely disposed from lower surface 69. Additionally, insulator 65 is provided with a pair of diametrically spaced circular openings 73, 75 respectively extending therethrough equidistant from the center axis thereof.

A pair of tubular sockets 77, 79 are frictionally engaged in respective openings 73, 75. Tubular sockets 77 79 are formed of a suitable metal that will conduct electricity and that is resilient. Also, tubular sockets 77, 79, before assembly with insulator 65, are slightly larger in diameter than the inside diameter of openings 73, 75 and are provided with slots 81, 83. Thus, in as sembling the parts, sockets 77, 79 are squeezed inwardly slightly to permit the sockets to enter openings 73, 75 and are held therein by the resiliency of the metal.

From the filament connecting points 37, 39, 41 and 43, the lead-in wires 31, 33 and 35 extend sealingly through step portion 23 into the hollow interior of stem 19 and to respective connecting points 47, 49 and 51. The leadin wires 31, 33 and 35 are connected as by soldering at points 47, 49 and 51 to sockets 77, 79 and collar 53, respectively. Thus, in referring to FIG. 1, it will be seen that the first and second lead-in wires 31, 33 connect respectively at points 47, 49 to respective first and second sockets 77, 79, and the third lead-in wire 35 connects at point 51 to collar 53. A ring of cement 84 fixedly attaches shell 17 to base 13, as is the conventional practice.

A current-directing plug 85 is selectively frictionally received in sockets 77, 79 by two prongs 87, 89. Prong 89 is insulated and serves to position the plug and is substantially an upwardly extended pin-like portion of circular 'body 91. Prong 87 is the current-directing prong and, as such, is integrally formed with contact disc 93.

3 Thus, as best shown in FIG. 3, prong 89 with body 91 and prong 87 with contact disc 93 are mating parts and fit together securely with conducting prong 87 extending through aperture 95 and contact disc 93 embedded in recessed portion 97 of body 91.

It is apparent that the position of plug 85, that is, the relative position of prongs 87, 89 with respect to sockets 73, 75, will determine the path of electrical current through the light bulb 11. Thus, when plug 85 is engaged in base 13 in the position shown in FIG. 1 and the bulb is screwed into an electrically charged receptacle, the current passes through contact disc 93, conducting prong 87, socket 77, lead-in wire 31, filament 27, lead-in wire 35, and collar 53 to complete the circuit and illuminatingly energize first filament 27. Conversely, when, with use, filament 27 burns in two and light bulb 11 fails to light, plug 85 is turned half around, and the current will then pass through contact disc 93, conducting prong 87, socket 79, lead-in wire 33, filament 29, lead-in wire 35, and collar 53, thereby energizing second filament 29.

Corresponding portions of plug body 91 and insulator conical surface 67 are preferably marked to indicate the position of the plug. By correspondingly marking the adjacent portions of the plugbody and insulator with color, indentations or the like, the condition of the filaments and, thus, the condition of the light bulb can readily be determined.

From the foregoing it can be seen that the present invention provides a light bulb having an extended period of usefulness for more effective lighting, which results in considerable saving of time, money and material. The invention further provides a light bulb particularly suitable for use, for safety reasons, in stop lights, caution lights and the like.

Although the invention has been described and illustrated with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited since changes and modifications may be made therein which are within the full intended scope of this invention as hereinafter claimed.

I claim:

In an incandescent lamp of the type having a sealed glass envelope and a base fixedly attached thereto, a first filament and a second filament, means mounting said first and second filaments in said envelope, a first socket and a second socket, insulating means mounting said first and second sockets in said base, a first lead-in wire connected adjacent one end of said first filament and sealingly extending through said mounting means to the exterior of said envelope and connected to said first socket, a second lead-in wire connected adjacent one end of said second filament and sealingly extending through said mounting means to the exterior of said envelope and connected to said second socket, a third lead-in wire respectively connected to the opposite ends of said first and second filaments from their respective connections with said first and second lead-in wires and with said third lead-in wire sealingly extending through said mounting means to the exterior of said envelope and connected to said base; a plug including a contact, an insulated prong, a conducting prong connected to said contact, and means fixedly interconnecting said insulated prong and said conducting prong to hold said insulated prong and said conducting prong in spaced parallel relationship; said plug being selectively manually movable between a first position and a second position, when in said first position said conducting prong being received in said first socket and said insulated prong being received in said second socket whereby said contact is connected to said first filament for lighting said first filament when said lamp is placed in a receptacle, and when in said second position said conducting prong being received in said second socket and said insulated prong being received in said first socket whereby said second filament is connected to said contact for lighting said second filament when said lamp is placed in a receptacle.

References Cited by the Examiner UNITED STATES PATENTS 8/1925 Brown 31568 1/1928 Kayte 31568 X JAMES W. LAWRENCE, Primary Examiner. 

